3D full field strain analysis of polymerization shrinkage in a dental composite

Abstract

Objective: The objective of this research was to study the polymerization shrinkage in a dental composite using 3D digital image correlation (DIC).

Methods: Using 2 coupled cameras, digital images were taken of bar-shaped composite (Premise Universal Composite; Kerr) specimens before light curing and after for 10 min. Three-dimensional DIC was used to assess in-plane and out-of-plane deformations associated with polymerization shrinkage.

Results: The results show the polymerization shrinkage to be highly variable with the peak values occurring 0.6-0.8mm away from the surface. Volumetric shrinkage began to significantly decrease at 3.2mm from the specimen surface and reached a minimum at 4mm within the composite. Approximately 25-30% of the strain registered at 5 min occurred after light-activation. Application of 3D DIC dental applications can be performed without the need for assumptions on the deformation field.

Significance: Understanding the local deformations and strain fields from the initial polymerization shrinkage can lead to a better understanding of the composite material and interaction with surrounding tooth structure, aiding in their further development and clinical prognosis.

Keywords: Dental composite stress analysis; Dental composites; Digital Image Correlation; Polymerization; Polymerization shrinkage; Strain.